The invention relates to an endoprosthesis, particularly as a replacement for shoulder and hip joints, comprising a prosthesis socket and prosthesis head firmly connected with a shaft, the surface of the prosthesis head engaging the surface of a chamber provided in the interior of the prosthesis socket to accommodate the prosthesis head.
Such endoprostheses may possibly prove difficult to install if the prosthesis head fits too tightly in the prosthesis socket. Under the influence of the tension generated by the ligaments and muscles, it is often difficult to bring the prosthesis head into its correct position if it is to be inserted into the prosthesis socket with a tight fit.
For this reason and to increase the freedom of movement of the prosthesis head in the prosthesis socket, it is known to enlarge the insertion opening provided in the prosthesis socket. With this measure, it becomes possible to substantially increase the freedom of movement of the prosthesis head in the prosthesis socket. However, there exists the danger that when the prosthesis socket is not in quite the proper position the prosthesis head will inadvertently pop out so that it must be reinserted in the prosthesis seat by a physician.